1. Field of the Invention
This invention pertains generally to methods and apparatus relating to wireless communication.
2. Description of Related Art
Wireless devices generally use antennas to communicate. The radio signals emanating from an antenna may be polarized. Polarization is the orientation of the plane of the wave radiated by an antenna. Polarization may be horizontal (linear), vertical (linear), elliptical, or circular (left or right hand) depending on the design of the antenna. The polarization of the antenna is determined by the orientation of the electric or E-field component within the area of radiation. A radio wave is transmitted and received with maximum intensity when the polarization of the transmitting antenna is substantially the same as the polarization of the receiving antenna. For example, maximum signal strength transfer occurs when the transmitting antenna has a horizontal polarization orientation and the receiving antenna has a horizontal polarization orientation. The radio signal strength communicated between two antennas decreases to the extent that the two antennas do not have the same polarization orientation. The signal strength between a first antenna and a second antenna reaches a minimum when the polarization orientation of the first antenna is orthogonal to the polarization orientation of the second antenna as, for example, when the first antenna has a horizontal polarization orientation and the second antenna has a vertical polarization orientation. Using antennas with different polarization orientations may be used to reduce interference between antennas.
The physical orientation of an antenna may determine its polarization orientation. Generally, antennas are mounted to achieve a desired polarization orientation and adjusted at the time of installation to increase transmission or reception of radio wave signal strength for the desired orientation.